There are some minerals such as silica, clay, andcalcium carbonate having been used in polyurethanematerials.3 In addition, fly ash (FA), a by-productfrom thermal power stations fuelled by pulverizedcoal, has been considered as a filler in different polymers It was reported that FAs improved thermalstability of some of polymer materials.5 Fly ashes asfillers have not been much examined with respect tothe production of polyurethane materials.6 BecauseFAs are by-product from the thermal power stations,and they are cheap and produced in great amountsin various countries throughout the world. Althoughsome amount of FAs find its way to industry, mostof them remains unused in the vicinity of power stations generating environmental pollution.There are different kinds of flame retardant materials such as alumina trihydrate,7 expandable graphite,8–12 alumina trihydrate and triphenylphosphate,7decabrominated dipheny ethane,10 melamine polyphosphate and melamine cyanurate,13 phosphorusmelamine-urea-formaldehyde,14 and aluminumphosphinate15 used in rigid polyurethane foams.Furthermore, the intumescent flame retardant systems have been considered in rigid polyurethanefoams.16 For example, ammonium polyphosphate(APP) as an intumescent flame retardant has beenused for polyurethane materials.8 Intumescent flameretardants including blowing agents work in theway that they decompose generating nonflammablegases resulting in the char that expands and
đang được dịch, vui lòng đợi..
